All Jaguar X-TYPE Diesel sedans and wagons are now Euro 4 emissions compliant—a year ahead of the date demanded by European legislation.

The new Euro 4 compliant X-TYPE 2.0 Diesel costs a bit extra (£500 in the UK, for example), but can offer a potential cut in the annual tax bill, depending upon the country. In the UK, the Euro 4-compliant Jag will allow users an approximate 3% reduction.

Jaguar maintained the basic parameters of the engine: peak power of 128 hp (95.6 kW) and torque of 330 Nm (243 lb-ft). To achieve the emissions reductions and improve the feel of the car, the company introduced a new engine management system, and modified the turbocharger with an electronic vane control device. The changes allow the engine and vehicle react faster and more efficiently to driver demand for more throttle, and better manage the combustion. Ford achieved Euro 4 emissions levels without using a particulate filter.

Fuel consumption and CO2 figures have increased slightly as a direct result of achieving the improved emissions status figures.

Comments

Very broadly speaking, you can decrease emissions (the regulated criteria/toxic kind, as in Euro-4) from a given engine by increasing the efficiency of the combustion in the cylinders, using cleaner fuel, by aftertreatments (catalysts, filters, etc.), or any combination of the three.

CO2 is a natural outcome of the combustion reaction. Combust the same amount of fuel more completely, and you’ll end up with more CO2.

Aftertreatment devices can also add to CO2. Oxidation catalysts, for example, convert the combustion byproducts of carbon monoxide (CO) and unburned hydrocarbons (HC) to CO2 and water.

That sounds like a bad deal, but it’s chemistry. The ideal (assuming you need to use a hydrocarbon-fueled combustion engine) would be to have a more efficient engine that allows you to downsize, thereby using less fuel. In other words, the slight increase in CO2 would be more than offset by the overall decrease in fuel consumption in a downsized, or just more efficient, engine.

In this particular case, though, it’s basically the same engine, but managed for better combustion.

You’ll note that there is also a fuel penalty. It’s a cleaner car than the pre-Euro-4 version, but it does burn slightly more fuel and produce more carbon dixoide.

The issue goes beyond this particular car. In a 1998 report, for example, Japan’s Transport
Engineering Council recommended an emission cut to
one-sixth (gasoline vehicles) and to one-third (diesel
vehicles) of the then current levels. At the same time, the Council predicted that such regulations would decrease fuel economy by 5% for diesels, 3% for conventional gasoline engines and 6% for direct injection gasoline engines—all having an adverse effect on CO2 emissions. (Burn more fuel, generate more CO2.)